Temporal and spatial variation analysis of the coastline of northwestern Hainan Island

Based on remote sensing technology and GIS, using high spatial resolution remote satellite SPOT-5 and GF-2 image data, the authors analyzed the northwestern coastlines of Nandu River in Haikou City-Dongfang City of Hainan Island at two different periods in 2005 and 2016 with human-machine interactive method, and temporal and spatial variation characters in the past 10 years. The results show that temporal and spatial variation of the coastline is significant in northwestern Hainan Island, and the major factor contributing to the variation is the artificial development and construction. The artificial coastline growth rate reached 113%, and its ratio was increasing from 24.3% in 2005 to 51.6% in 2016. The parts of sludge shoreline and sand coastline were conversed to artificial coastline, and the natural coastline mainly suffered from erosion, with only a small amount of coastline being silted. Different coastlines have different variations. Danzhou City and Chengmai County are rich in coastline resources, with large development degree. Lingao County and Changjiang Li Autonomous County natural coastline is dominated by erosion, with less siltation. Dongfang City and Chengmai County have less coastline erosion and are more prone to siltation. The analysis results would provide some scientific reference for the investigation,development and protection of northwestern coastlines of Hainan Island.